PHP Comparison Logic Quiz

During an authorization review, why do staff engineers treat comparison rules as part of the security surface rather than a mere style preference?

Debug logs show this snippet. What appears in the terminal?

<?php
var_dump('15' == 15);
var_dump('15' === 15);
?>

A reviewer asked about the spaceship operator. What does this code print?

<?php
$a = 5;
$b = '5';
echo $a <=> $b;
?>

When checking case-sensitive product codes sent as strings, why do architects recommend strcmp over ==?

A teammate demonstrates falsy pitfalls. What does this snippet output?

<?php
var_dump('0' == 0);
var_dump('0' === 0);
?>

Incident response highlights why switch requires caution. What line prints?

<?php
$value = '0e1234';
switch ($value) {
    case 0:
        echo 'zero branch';
        break;
    default:
        echo 'default branch';
}
?>

Why do code reviews require a justification when someone uses == in conditionals?

What does this membership check print?

<?php
$allowed = [0, 1];
echo in_array('0', $allowed, true) ? 'allowed' : 'denied';
?>

When writing comparator callbacks for usort, why must the function return -1, 0, or 1 consistently?

A teammate demonstrates boolean coercion. What prints?

<?php
var_dump(true == '1');
var_dump(true === '1');
?>

When comparing floating-point totals from two services, why should reviewers ask for a tolerance threshold instead of direct equality?

What does this tolerance snippet output?

<?php
$a = 0.1 + 0.2;
$b = 0.3;
echo abs($a - $b) < 0.0001 ? 'close' : 'far';
?>

Why do naming conventions recommend prefixing boolean variables with verbs such as $isActive or $canShip when writing comparison-heavy code?

A developer evaluates locale-sensitive strings. What does this snippet print?

<?php
setlocale(LC_COLLATE, 'C');
echo strcasecmp('straße', 'STRASSE') === 0 ? 'equal' : 'different';
?>

During API reviews, why do teams document whether comparison decisions should be lexicographic or numeric when interpreting IDs?

What does this snippet reveal about boolval?

<?php
echo boolval('false') ? 'true branch' : 'false branch';
?>

Why is logging both operands of a critical comparison useful during incident investigations?

A pull request shows this helper. What does it print?

<?php
$input = '15';
echo filter_var($input, FILTER_VALIDATE_INT) === false ? 'reject' : 'accept';
?>

When comparing version strings, why is version_compare preferred over manual string operators?

What is echoed by this null-coalescing comparison?

<?php
$value = '';
echo $value === '' ? 'empty string' : 'other';
?>

When reading SQL result sets, why should engineers avoid comparing numeric columns as strings when they come from loosely typed drivers?

What does this comparator reveal?

<?php
$values = [2, '02', 10];
usort($values, function ($a, $b) {
    return $a <=> $b;
});
echo implode(',', $values);
?>

Why do coding standards forbid comparing DateTime instances with ==?

A migration script checks the result of strcmp. What does it echo?

<?php
echo strcmp('005', '5') === 0 ? 'same' : 'different';
?>

Why should business rules specify whether a comparison is inclusive or exclusive when dealing with time windows?

What does this strict inequality print?

<?php
$limit = 100;
$input = '100';
echo $input < $limit ? 'below' : 'not below';
?>

Why do API clients rely on descriptive constants (e.g., Status::SUCCESS) instead of bare integers when comparing response codes?

What does this nullsafe comparison echo?

<?php
$user = null;
echo $user?->role === 'admin' ? 'admin' : 'guest';
?>

Product managers ask how tie-breakers work in multi-field sorts. Why do engineers often chain comparisons rather than nest if statements?

Why do teams document the intent behind "magic" sentinel values (like -1 meaning unlimited) before comparing them inside business logic?